Sink



FIG. 1 is a top, front, left perspective view of a sink in accordance with our design;

FIG. 2 is a rear elevational view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a right side elevational view thereof;

FIG. 5 is a left side elevational view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom view thereof.

The broken lines shown form no part of the claimed design. 

CLAIM The ornamental design for a sink, as shown and described. 